import {
  embeddedAgentLog,
  resolveEmbeddedAgentRuntime,
  type CompactEmbeddedPiSessionParams,
  type EmbeddedPiCompactResult,
} from "openclaw/plugin-sdk/agent-harness";
import {
  getSharedCodexAppServerClient,
  type CodexAppServerClient,
  type CodexServerNotificationHandler,
} from "./client.js";
import { isJsonObject, type CodexServerNotification, type JsonObject } from "./protocol.js";
import { readCodexAppServerBinding } from "./session-binding.js";

type CodexAppServerClientFactory = () => Promise<CodexAppServerClient>;
type CodexNativeCompactionCompletion = {
  signal: "thread/compacted" | "item/completed";
  turnId?: string;
  itemId?: string;
};
type CodexNativeCompactionWaiter = {
  promise: Promise<CodexNativeCompactionCompletion>;
  startTimeout: () => void;
  cancel: () => void;
};

const DEFAULT_CODEX_COMPACTION_WAIT_TIMEOUT_MS = 5 * 60 * 1000;

let clientFactory: CodexAppServerClientFactory = getSharedCodexAppServerClient;

export async function maybeCompactCodexAppServerSession(
  params: CompactEmbeddedPiSessionParams,
): Promise<EmbeddedPiCompactResult | undefined> {
  const runtime = resolveEmbeddedAgentRuntime();
  const provider = params.provider?.trim().toLowerCase();
  const shouldUseCodex =
    runtime === "codex" ||
    (runtime === "auto" && (provider === "codex" || provider === "openai-codex"));
  if (!shouldUseCodex) {
    return undefined;
  }

  const binding = await readCodexAppServerBinding(params.sessionFile);
  if (!binding?.threadId) {
    if (runtime === "codex") {
      return { ok: false, compacted: false, reason: "no codex app-server thread binding" };
    }
    return undefined;
  }

  const client = await clientFactory();
  const waiter = createCodexNativeCompactionWaiter(client, binding.threadId);
  let completion: CodexNativeCompactionCompletion;
  try {
    await client.request("thread/compact/start", {
      threadId: binding.threadId,
    });
    embeddedAgentLog.info("started codex app-server compaction", {
      sessionId: params.sessionId,
      threadId: binding.threadId,
    });
    waiter.startTimeout();
    completion = await waiter.promise;
  } catch (error) {
    waiter.cancel();
    return {
      ok: false,
      compacted: false,
      reason: formatCompactionError(error),
    };
  }
  embeddedAgentLog.info("completed codex app-server compaction", {
    sessionId: params.sessionId,
    threadId: binding.threadId,
    signal: completion.signal,
    turnId: completion.turnId,
    itemId: completion.itemId,
  });
  return {
    ok: true,
    compacted: true,
    result: {
      summary: "",
      firstKeptEntryId: "",
      tokensBefore: params.currentTokenCount ?? 0,
      details: {
        backend: "codex-app-server",
        threadId: binding.threadId,
        signal: completion.signal,
        turnId: completion.turnId,
        itemId: completion.itemId,
      },
    },
  };
}

function createCodexNativeCompactionWaiter(
  client: CodexAppServerClient,
  threadId: string,
): CodexNativeCompactionWaiter {
  let settled = false;
  let removeHandler: () => void = () => {};
  let timeout: ReturnType<typeof setTimeout> | undefined;
  let failWaiter: (error: Error) => void = () => {};

  const promise = new Promise<CodexNativeCompactionCompletion>((resolve, reject) => {
    const cleanup = (): void => {
      removeHandler();
      if (timeout) {
        clearTimeout(timeout);
      }
    };
    const complete = (completion: CodexNativeCompactionCompletion): void => {
      if (settled) {
        return;
      }
      settled = true;
      cleanup();
      resolve(completion);
    };
    const fail = (error: Error): void => {
      if (settled) {
        return;
      }
      settled = true;
      cleanup();
      reject(error);
    };
    failWaiter = fail;
    const handler: CodexServerNotificationHandler = (notification) => {
      const completion = readNativeCompactionCompletion(notification, threadId);
      if (completion) {
        complete(completion);
      }
    };
    removeHandler = client.addNotificationHandler(handler);
  });

  return {
    promise,
    startTimeout(): void {
      if (settled || timeout) {
        return;
      }
      timeout = setTimeout(() => {
        failWaiter(new Error(`timed out waiting for codex app-server compaction for ${threadId}`));
      }, resolveCompactionWaitTimeoutMs());
      timeout.unref?.();
    },
    cancel(): void {
      if (settled) {
        return;
      }
      settled = true;
      removeHandler();
      if (timeout) {
        clearTimeout(timeout);
      }
    },
  };
}

function readNativeCompactionCompletion(
  notification: CodexServerNotification,
  threadId: string,
): CodexNativeCompactionCompletion | undefined {
  const params = notification.params;
  if (!isJsonObject(params) || readString(params, "threadId", "thread_id") !== threadId) {
    return undefined;
  }
  if (notification.method === "thread/compacted") {
    return {
      signal: "thread/compacted",
      turnId: readString(params, "turnId", "turn_id"),
    };
  }
  if (notification.method !== "item/completed") {
    return undefined;
  }
  const item = isJsonObject(params.item) ? params.item : undefined;
  if (readString(item, "type") !== "contextCompaction") {
    return undefined;
  }
  return {
    signal: "item/completed",
    turnId: readString(params, "turnId", "turn_id"),
    itemId: readString(item, "id") ?? readString(params, "itemId", "item_id", "id"),
  };
}

function resolveCompactionWaitTimeoutMs(): number {
  const raw = process.env.OPENCLAW_CODEX_COMPACTION_WAIT_TIMEOUT_MS?.trim();
  const parsed = raw ? Number.parseInt(raw, 10) : NaN;
  if (Number.isFinite(parsed) && parsed > 0) {
    return parsed;
  }
  return DEFAULT_CODEX_COMPACTION_WAIT_TIMEOUT_MS;
}

function readString(params: JsonObject | undefined, ...keys: string[]): string | undefined {
  if (!params) {
    return undefined;
  }
  for (const key of keys) {
    const value = params[key];
    if (typeof value === "string") {
      return value;
    }
  }
  return undefined;
}

function formatCompactionError(error: unknown): string {
  if (error instanceof Error) {
    return error.message;
  }
  return String(error);
}

export const __testing = {
  setCodexAppServerClientFactoryForTests(factory: CodexAppServerClientFactory): void {
    clientFactory = factory;
  },
  resetCodexAppServerClientFactoryForTests(): void {
    clientFactory = getSharedCodexAppServerClient;
  },
} as const;